9.9MB for a 450 page document sounds quite small, actually — unless there's some major concern about the filesize, I would leave it as-is. If the major concern about the filesize comes from someone else, I would try to educate them.
I work on graphically-heavy books, and they usually end up being about 10MB per 100 pages, with similar features to your title (bookmarks, hyperlinks, TOC, live layers). The export to PDF preset that I use is here: http://dirtywords.tv/2011/inde…..df-preset/
I do end up manipulating the files slightly in Acrobat after exporting, but I stay away from the Save As/PDF Optimizer settings, as they often introduce JPG2000 compression which doesn't render properly on iOS devices.